A mangrove stand under sewage pollution stress: Red Sea

A mangrove stand of Avicennia marina located at the South Corniche of Jeddah city receives about 100 000 m³ of sewage per day. The sewage has high values of BOD, COD, nutrient concentrations, heavy metals and faecal coliform counts.The mangrove stand is very small and occupies an area of about 0.45 km². The trees are stunted with low pneumatophore density. The pneumatophore distribution is restricted to the area of substrate underneath the plant crown covers and they do not look healthy. A high proportion of them was observed to be dead and/or aberrant. These abnormal induced features were attributed to the sewage discharge in the area. The death of pneumatophores decreases the aeration area which apparently affects the respiration rate of the root system, nutrient uptake and plant growth, consequently leading to a retarded growth of the mangroves.